Design optimization of LMS-based adaptive equalizer for ZigBee systems with fading channels

Abstract

ZigBee is considered as one of the most commonly used standards in wireless sensor networks (WSNs). Minimizing the effect of multipath fading channels is crucial for any network performance. This paper investigates the influence of fading channels on the performance of ZigBee using IEEE 802.15.4 PHY layer with direct sequence spread spectrum (DSSS) technique and offset quadrature phase shift keying (OQPSK) modulation. Least mean square adaptive linear equalizer (LMS ALE) is combined to the system to minimize the channel effects. Performance and design analysis are presented in details. In addition, two design optimization procedures for the adaptive equalizer based on genetic algorithm (GA) and particle swarm optimization (PSO) are proposed. The multi-objective optimizations aim to choose the equalizer design parameters that achieve the optimum ZigBee transceiver steady-state and transient performance. For verification purposes, the proposed design is simulated and tested in MatLab environment at different network scenarios. The results certify the ability of the proposed technique to extract the original transmitted signal at the receiver with minmum bit error rate (BER) and maximum speed of adaptation.